"It's not right for us"

Ah yes, the catch all phrase.
Miss Snark uses a variation of this.
If you apply gin to the paper, the invisible writing comes through. It says "this is the suckiest thing in my slush pile since Paris Hilton's novel"

Let's look at some numbers: 85% of the material I get is unpublishable. That's a LOT of crap in the slush pile. Is yours crap? I don't know. Email me the first page and I'll tell you. (IMPORTANT UPDATE)....email the page AND let me know it's ok to publish it on the blog.
I'll leave your name off, but Im not doing one on one private audiences.

Of the remaining 15% a hefty dose are in areas I don't represent or feature themes I think are repulsive. So "not right for me" in this case means, I can't stand it but someone else might.

And sometimes "not right for me" means I'm too lazy to say anything else. It's a form letter.

As a writer approaching agents you must walk with the grace of a ballerina and have the skin of a rhino.

Like Kremlinologists of old, writers try to deconstruct the meaning of every word, comma and lipstick smear on correspondence. Stop it.

Don't look at what people say but how often you hear it. If you send 100 query letters and get back NOTHING helpful, it IS you. You need some outside assistance.

If you're getting back dribs and drabs of helpfulness, pay attention to that.
If you're getting back letters that say "not this but keep me in mind for other things" pay close attention. Miss Snark NEVER fucks around with that phrase. When you hear that, it's real.